PS> ls c:\windows\*.exe | get-fileversion

ProductVersion   FileVersion      FileName
--------------   -----------      --------
1.6.0.2          1.6.0.2          C:\windows\Alcmtr.exe
1.1.0.27         1.1.0.27         C:\windows\alcwzrd.exe
6.00.2900.2180   6.00.2900.218... C:\windows\explorer.exe
5.2.3790.2453    5.2.3790.2453... C:\windows\hh.exe
5, 51            5, 51, 138, 0    C:\windows\IsUninst.exe
1.1.0.8          1.1.0.8          C:\windows\MicCal.exe
5.1.2600.2180    5.1.2600.2180... C:\windows\NOTEPAD.EXE
5.1.2600.2180    5.1.2600.2180... C:\windows\regedit.exe
2.0.1.7          2.0.1.7          C:\windows\RTHDCPL.exe
1.0.1.51         1.0.1.51         C:\windows\RTLCPL.exe
2, 5, 0, 5       2, 5, 0, 5       C:\windows\RtlUpd.exe
1, 0, 0, 21      1, 0, 0, 21      C:\windows\SoundMan.exe
5.1.2600.0       5.1.2600.0 (x... C:\windows\TASKMAN.EXE
1,7,0,0          1,7,0,0          C:\windows\twunk_16.exe
1,7,1,0          1,7,1,0          C:\windows\twunk_32.exe
3.10.425         3.10.425         C:\windows\winhelp.exe
5.1.2600.2180    5.1.2600.2180... C:\windows\winhlp32.exe

PS> get-fileversion C:\monad\rc1\System.Management.Automation.dll

ProductVersion   FileVersion      FileName
--------------   -----------      --------
1.0.9567.1       1.0.9567.1       C:\monad\rc1\System.Management.Automation.dll

param ( [string[]]$paths )
begin {
    # I want to do some stuff with relative paths.   
    # create a variable that I can use later
    $P = [string](get-location)

    # the workhorse of the script
    function GetVersionInfo
    {
        param ( [string]$path )
        # resolve the path, we're going to need a fully qualified path to hand
        # to the method, so go get it.  I may not have that depending on how
        # was called
        $rpath = resolve-path $path 2>$null
        # the thing we hand to the method is the path string, so we'll tuck that away
        $path = $rpath.path
        # check to be sure that we're in the filesystem
        if ( $rpath.provider.name -ne "FileSystem" ) 
        { 
            "$path is not in the filesystem"
            return $null
        }
        # now that I've determined that I'm in the filesystem, go get the fileversion
        $o = [system.diagnostics.fileversioninfo]::GetVersionInfo($path)
        # this little dance adds a new property to the versioninfo object
        # I add the relative path to the versioninfo so I can inspect that in the output object
        # the way that add-member works is to not emit the object, so I need to 
        # use the -passthrough parameter
        $o|add-member noteproperty RelativePath ($path.replace($P,".")) -pass
    }
    # whoops! something bad happened
    function ShowFileError
    {
        param ( [string]$path )
        if ( test-path $path -pathtype container )
        {
            "$path is a container"
        }
        else
        {
            "$path not found"
        }
    }
}

# data could have been piped - check $_ to see if this cmdlet had data
# piped to it
process {
    if ( $_ )
    {
        # make sure that I'm not trying to get a versioninfo of a directory
        if ( test-path $_ -pathtype leaf )
        {
            GetVersionInfo $_
        }
        else
        {
            ShowFileError $_
        }
    }
}

# we could have also gotten arguments on the command line
end {
    if ( $paths )
    {
        # by calling resolve path first, I can deal with wildcards on the command line
        foreach ( $path in resolve-path $paths )
        {
            # make sure it's a file, not a directory
            if ( test-path $path -pathtype leaf )
            {
                GetVersionInfo $path
            }
            else
            {
                ShowFileError $path
            }
        }
    }
}